A STUDY ON TROUT AND YOUNG SALMON. 245 



sizes as the young salmon have been kept in the aquarium 

 where the latter were reared. 



The fænomenon however is in good harmony with the well 

 known propensities of the trouts for variation. 



Before entering into a closer description of the younger 

 stages of salmon, compared with trout of the same sizes, I 

 will shortly relate the result of my search in those of Scandi- 

 navian museums whose collections of salmon I have had the 

 opportunity of examining. 



In Norwegian museums I have only succeded in finding 4: 

 salmon between 16 and 45 cm. 's length. None of these have 

 ever been described. 



In the Bergen museum I found 2 young salmon resp. 20,5 

 cm. and 21,5 cm. long. They were reared in a freshwater dam 

 in Jæderen and by Mr. Grude presented to the Bergen mu- 

 seum. 



They both closely resemble the fishes reared by me in salt 

 water. 



In the university museum in Christiania I also found 2 sal- 

 mon resp. 23,5 cm. and 28 cm. long. They had not been sub- 

 jected to any closer examination or been described. According 

 to professor Collett they were found among mackerel in the 

 Christiania fish market. 



Also these closely correspond with the fishes reared by me 

 and differ, as also do the fishes from the Bergen museum, most 

 decidedly from any salmonid fish of similar size wich I have 

 ever cought in the sea. 



In plates I, II and III will be found drawings representing 

 as well these young salmon as trout of corresponding sizes. In 

 my opinion a superficial glance is quite sufificent in order to 

 discover the considerable difference between then. Later on a 

 closer description will be given. 



Before doing this however we need to review the collec- 

 tions, forming the base of the diagnostical descriptions issued 



